Abstract: Helium-hydrogen separation bed is an important part of fusion reactor tritium extraction system. Its flow resistance characteristics affect the adsorption efficiency and system resistance. Radial adsorption bed structure can reduce the resistance. The main structure of the radial flow helium-hydrogen separation bed is composed of the central metal powder layer and the inner and outer filters that support the powder layer. The flow resistance of the bed is mainly composed of the central powder layer resistance and the inner-outer filter resistance. In this paper, the resistance characteristics of the filter and porous media were obtained by flow resistance experiment, and a two-dimensional numerical model of the fluid flow in a radial helium-hydrogen separation bed was developed using COMSOL software. The characteristic parameters were obtained by fitting the simulation software. The flow mechanism of fluidized bed was further studied by using this model to provide guidance for structural design and parameter optimization. The results show that combined with the experimental data of the single-layer sintered screen filter, the parameters of the screen filter resistance model are established, and the parameters of A₁ and B₁ are obtained (A₁=3.234×10⁶, B₁=2.956×10⁷), and the resistance model of the double-layer screen filter is also established and compared with the experimental data with good coincidence, which verifies the reliability of the mathematical model. During the validation of the powder layer resistance characteristics parameters, it is found that the Ergun model parameters could better fit the experimental resistance when the powder particle size is large (R_p=125 μm). However, with the decrease of the powder particle size, the difference between the resistance values obtained by the Ergun model parameters and the experimental values gradually increases, the model parameters should be further modified. When the fluid flows through the porous layer of the bed, the resistance pressure drop is mainly composed of the viscous and inertial components, which are changing with the inlet flow rate. The share of the viscous and inertial terms in the resistance pressure drop was calculated. Through the analysis of flow mechanism, it is found that the resistance of screen filter is mainly inertia resistance, which changes in parabola with the increase of equivalent Reynolds number. The bed powder resistance is mainly the viscous resistance, which varies linearly with the increase of equivalent Reynolds number. Brinkman mathematical model can better describe the physical variation law of fluid flow in different types of porous media, and can be used to analyze the variation law of viscous term and inertia term of porous media.